A thermoelectric technology, such as thermoelectric power generation and thermoelectric cooling field, has been used to directly convert heat energy into electric energy or electric energy to heat energy in a solid state. As thermoelectric performance of a thermoelectric material used for thermoelectric power generation and thermoelectric cooling has been improved, performance of a thermoelectric module manufactured using the thermoelectric material may be further improved.
Examples of physical properties of the thermoelectric material determining the thermoelectric performance may include thermoelectromotive force (V), a Seebeck coefficient (S), a Peltier coefficient (π), a Thomson coefficient (τ), a Nemst coefficient (Q), an Ettingshausen coefficient (P), electrical conductivity (σ), a power factor (PF), a figure of merit (Z), a dimensionless figure of merit
            (               ⁢    ZT    =                              s          2                ⁢        σ            κ        ⁢    T  (T: absolute temperature)), thermal conductivity (κ), a Lorentz number (L), electric resistivity (ρ), and the like. Among them, a dimensionless figure of merit (ZT) may be an important physical property for determining thermoelectric conversion energy efficiency, and by using a thermoelectric material with a large figure of merit
      (          Z      =                                    s            2                    ⁢          σ                κ              )    ,power generation efficiency ana cooling efficiency may be increased when manufacturing a thermoelectric module. In other words, the higher the Seebeck coefficient and the electrical conductivity of the thermoelectric material may be able to provide the lower the thermal conductivity of the thermoelectric material thereby substantially improving thermoelectric performance of the thermoelectric material.
Currently, commercialized thermoelectric materials may include a Bi—Te based thermoelectric material for room-temperature applications, Pb—Te based and Mg—Si based thermoelectric materials for mid-temperature applications, a Fe—Si based thermoelectric material for high-temperature applications, and the like, based on the temperature for operating. However, since these thermoelectric materials have been mostly prepared by sintering metal powders, obtaining a thermoelectric material having excellent mechanical properties may be limited. Particularly, since the Mg—Si based thermoelectric material has low compressive strength due to brittleness, cracks may occur in the thermoelectric material during a process of manufacturing a thermoelectric module. Further, since the Mg—Si based thermoelectric material has low facture toughness as compared to other thermoelectric materials, the Mg—Si based thermoelectric material may not withstand impacts applied during a process of repetitively using the thermoelectric module, and may be broken, such that a lifetime of the thermoelectric module may be decreased.